The present invention relates to a scintigraphic device of the kind comprising: a case open at an application end and coated with a shielding shell; a collimator made of a material with high atomic number and high density and having a plurality of collimation channels extending substantially parallel to each other according to a predefined direction of measurement, the collimator being positioned inside the case in such a way as to allow the passage of radiation directed substantially parallel to the direction of measurement; a measuring member positioned inside the case in proximity to the collimator and comprising at least one converter able to convert each ionizing radiation coming from a source in exam in light radiation and at least one photosensor for determining the energy associated to each event and its position in the visual field; at least one electronic processing unit operatively associated to the photosensor.
The present invention is aimed at the diagnostic medical sector, and in particular, it is dedicated to the location of tumor lesions and similar pathologies or to the observation of radio marked substances, introduced into the organisms before the exam to be conducted in order to visualize the distribution of the introduced substance.
As is well known, the systems for locating and visualizing the distribution of radioactivity, such as those illustrated and described in the U.S. Pat. Nos. 6,242,744 B1 and U.S. Pat. No. 6,232,605 B1, operate on particularly small visual fields and are used in Nuclear Medicine as locating and diagnostic device able to identify neoplasias with high spatial resolution. It is also known that the aforementioned devices are used to carry out scintigraphic analyses on small animals, to test new radio-marked antibodies, specific for determined pathologies. It is also possible that said scintigraphic devices are used for the guided location of lesions of the prostate and of the breast, in order to identify the regions subjected to high capture to be subjected to bioptic sampling, integrating current radiographic and/or echographic techniques. These devices can also find additional applications in Astrophysics and in systems for industrial non destructive checks.
More specifically, the main use of the aforementioned device pertains to the location of tumor lesions, especially in those techniques that require an adequate precision in detection such as biopsies (prostate and breast) or in radio-guided or radio-immunoguided interventions during which the detected signals are converted in digital form to provide necessary information through light or sound scales related to the intensity of the signals that fall within the selected energy window.
Although known technologies allow quite precise diagnoses, the Applicant has noted that they are nonetheless not free of some drawbacks, mainly in relation to spatial resolution in general, and in particular, to the spatial resolution of about one centimeter, as well as to the dimensions and to the overall masses of the current gamma-cameras present on the market.
These problems, along with a growing and necessary demand for definition and spatial resolutions of the aforementioned diagnostic instruments and/or devices, have already been confronted in the U.S. Pat. Nos. 6,242,744 and U.S. Pat. No. 6,232,605 (Soluri et al.), U.S. Pat. No. 5,783,829 (Sealock et al.), U.S. Pat. No. 5,864,141 (Majewski et al.), U.S. Pat. No. 6,021,341 (Scibilia et al.) and in the international patent WO 96/37791 (De Notaristefani et al.). This notwithstanding, in some applications the required spatial resolutions is a fundamental parameter, so still higher resolutions must be obtained. The achievement of a high spatial resolutions, however, is hindered by inaccuracies in the location of one or more events detected by the scintillation crystals. This drawing persists even if to the crystal matrices are associated last generation photomultipliers, or photo tubes, known as PSPMT (Position Sensitive Photomultiplier Tube) and a high resolution lead collimator, generally provided with hexagonal holes. It is also detectable in the presence of scintillation crystals positioned inside the individual holes of the collimators or of planar elements positioned at the collimators, as described in U.S. Pat. No. 6,734,430 (Soluri et al.).
Another factor able negatively to influence the spatial resolution of the aforementioned diagnostic devices is the length of the respective collimators, unsuitable for the type of exam to be performed, as well as the distance of the lesions to be detected and located with respect to the scintillation crystals. In general, the difficulty in locating lesions increases as a function of their distance from the detector.
Usually, scintigraphic devices are provided with collimators with fixed length, chosen and mounted according to the type of exam or detection to be carried out. The collimators may also be replaced by other collimators with different structural characteristics. However, the complicated operation of replacing the collimators is rarely performed to execute particular exams that require a different spatial resolution or counting efficiency from those normally in use.